1. Field of the Invention
This invention relates generally to a system and method for registering range images from multiple LiDAR sensors and, more particularly, to a system and method for registering range images from multiple LiDAR sensors on a vehicle, where the method includes registering two frames of data from the multiple LiDAR sensors at the same time.
2. Discussion of the Related Art
Many modern vehicles include object detection sensors that are used to enable collision warning or avoidance and other active safety applications. The object detection sensors may use any of a number of detection technologies, such as short range radar, cameras with image processing, laser or LiDAR, ultrasound, etc. The object detection sensors detect vehicles and other objects in the path of a host vehicle, and the application software uses the object detection information to provide warnings or take actions as appropriate. In many vehicles, the object detection sensors are integrated directly into the front bumper or other fascia of the vehicle.
In order for the application software to perform optimally, the object detection sensors must be aligned properly with the vehicle. For example, if a sensor detects an object that is in the path of the host vehicle but, due to sensor misalignment, the sensor determines that the object is slightly to the left of the path of the host vehicle, this can have significant consequences for the application software. Even if there are multiple forward looking object detection sensors on a vehicle, it is important that they are all aligned properly, so as to minimize or eliminate conflicting sensor readings.
LiDAR sensors are one type of sensor that are sometimes employed on vehicles to detect objects around the vehicle and provide a range to those objects. LiDAR sensors are desirable because they are able to provide the heading of a tracked object, which other types of sensors, such as vision systems and radar sensors, are generally unable to do. For one type of LiDAR sensor, reflections from an object are returned as a scan point as part of a point cluster range map, where a separate scan point is provided for every ½° across the field-of-view of the sensor. Therefore, if a target vehicle is detected in front of the host vehicle, there may be multiple scan points that are returned that identify the distance of the target vehicle from the host vehicle.
A vehicle may have multiple LiDAR sensors to provide a 360° field-of-view around the vehicle. These multiple LiDAR sensors may include side looking sensors, rearward looking sensors and forward looking sensors. Each of the sensors track objects in its field-of-view independently of the other sensors. Using the scan point returns from the multiple sensors, the range map is generated to track objects in proximity to the host vehicle. For a vehicle with multiple LiDAR sensors, multiple point cluster maps are returned, and for over-lapping sensor field-of-views, the sensors may be tracking the same object. It is necessary to combine the scan point maps of the sensors so that the same object tracked by the sensors is processed as a single target.
U.S. patent application Ser. No. 12/942,456, titled, Systems and Methods for Tracking Objects, filed Nov. 9, 2010, assigned to the assignee of this application and herein incorporated by reference, discloses a technique for monitoring the range and heading of a target object from a host vehicle using LiDAR sensors. This application is limited to a single LiDAR sensor, and does not discuss fusing returns from multiple LiDAR sensors.